The long-term objective of this research is to identify behavioral correlates that may help in differential diagnosis and provide a measure of cholinergic functioning in patients with Alzheimer's Disease/Senile Dementia of the Alzheimer Type (ALZ) vs. Multi-Infarct Dementia (MID). Previous research suggests that one such behavior is likely to be the intrusion of irrelevant responses into the free recall of unrelated words. Two hundred-fifty outpatients referred for dementia will each be tested with one of 15 different lists of 12 unrelated words on 12 trials of free recall with selective reminding. Intrusions, as well as the order of all output, will be recorded. A mental status and functional inventory will be given to determine the degree of dementia and other tests will be given to describe the group and to measure aspects of the research diagnostic criteria (RDC). Neurological diagnoses will be obtained using RDC for ALZ and MID. The number of different intrusions and the number of intrusions not semantically related to the stimuli will be counted. The relationship between ALZ (vs. MID) and the presence of intrusions on this task will be investigated and the specificity and sensitivity of intrusions as a sign of ALZ will be determined. The association of the number of different intrusions and the degree of dementia will be ascertained.